Preparation method and application of encapsulated electrothermal phase change fiber with axially oriented conductive network

Abstract

The present invention discloses a method for preparing an encapsulated electrothermal phase change fiber with an axially oriented conductive network, comprising: first dissolving carbon black in water and dispersing it, then adding methyl cellulose to prepare a carbon black / methyl cellulose spinning solution; then squeezing the spinning solution into a cold source through a spinning needle on an injection pump, whereupon the spinning solution gradually freezes upon entering the cold source, and collecting the frozen fibers to prepare carbon black / methyl cellulose aerogel fibers with differently oriented conductive network structures; immersing the carbon black / methyl cellulose aerogel fibers in a molten phase change material, vacuum impregnating, and then cooling to obtain an electrothermal phase change fiber; and coating the electrothermal phase change fiber with a polymer solution by dip coating, and allowing the solvent to evaporate to prepare a shell encapsulation to obtain an encapsulated electrothermal phase change fiber. The encapsulated electrothermal phase change fiber prepared by this method has high electrical conductivity, high energy storage density, high electrothermal conversion efficiency, excellent flexibility and stability, and outstanding thermal management capabilities.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive fiber materials composited with phase change materials, and in particular to a preparation method and application of an encapsulated electrothermal phase change fiber with an axially oriented conductive network. Background Art

[0002] In recent years, many advanced personal thermal management textiles have emerged and have received widespread attention and research from industry and academia. These intelligent thermal management textiles maintain human thermal comfort by regulating thermal radiation, thermal conduction, and humidity. For example, Omni-heat, a thermal insulation fabric developed by Columbia, has an inner layer of high-infrared reflectivity material that can improve thermal insulation by suppressing human thermal radiation. Thermolite, a polyester hollow fiber developed by DuPont in the United States, can capture air, limit heat conduction and convection, and thus enhance the thermal insulation capacity of clothing. In addition, some personal thermal management textiles use external energy input, such as through electrothermal and thermoelectric effects, to achieve active heating or cooling effects.

[0003] Among the many personal thermal management textiles, textiles composited with phase change materials (PCMs) can store or release thermal energy through a reversible phase change process, mitigating the adverse effects of ambient temperature fluctuations on the human body and providing enhanced temperature regulation capabilities in environments with drastic temperature fluctuations. Benefits of PCMs: PCMs are advanced functional materials that can absorb or release significant amounts of latent heat through reversible melting or crystallization processes within a narrow phase change temperature range. For example, some solid-liquid PCMs can absorb or release approximately 200 to 300 J / g of latent heat during their phase change. The energy storage properties of PCMs give them significant potential for application in personal thermal management. As early as the 1970s, NASA employed PCMs in the development of spacesuits and spacecraft to protect personnel and equipment from damage in the extreme temperatures of space. Phase change materials commonly used in phase change textiles are solid-liquid phase change materials, such as paraffin waxes, aqueous inorganic salts, and organic phase change materials like polyvinyl alcohol. Their phase change temperatures match the human thermal comfort range, approximately between 15°C and 35°C, ensuring enhanced thermal comfort when worn. The working mechanism of phase change textiles: When the ambient temperature rises, the phase change material in the textile undergoes a solid-to-liquid phase change, absorbing heat. Because heat is absorbed and stored as phase change energy in the phase change material, the overall temperature of the textile does not immediately rise. This phase change energy storage mechanism ensures that the textile cools down when the ambient temperature is high, alleviating the sensation of dryness and heat. When the ambient temperature drops, the phase change material transitions from liquid to solid, converting the phase change energy into heat and releasing it to maintain a constant temperature in the textile. Therefore, phase change textiles can provide heat to the human body in cold environments, preventing hypothermia and frostbite.

[0004] Although phase change textiles have excellent thermal management capabilities, relying solely on the phase change thermostat mechanism is unable to meet human thermal management needs for advanced textiles with long service cycles, wide applications, and active thermal regulation. There is an urgent need to develop electrothermal phase change textiles with phase change thermostat, active heating, and energy storage functions. Preparation method of electrothermal phase change textiles: Since commonly used phase change materials are electrically insulating, it is necessary to add conductive fillers to the electrothermal phase change textiles to construct a conductive network in order to achieve electrothermal conversion. Commonly used conductive fillers include metal materials and their alloys (such as silver, gold, etc.); carbon-based conductive materials (such as graphene, carbon nanotubes, graphite foam, conductive carbon black and biomass carbon, etc.); conductive polymers (such as polypyrrole, polyaniline, etc.); two-dimensional transition metal carbide / nitride materials MXene (such as Ti3C2Tx). In the existing technology, electrothermal phase change fibers are generally obtained by blending conductive materials, phase change materials and polymer materials and then spinning them through melt spinning, wet spinning and other technologies, or by coating conductive materials on the surface of phase change textiles.

[0005] For example, the Chinese patent with publication number CN 108587571 A prepares graphene aerogel fibers by wet spinning and chemical reduction, then combines the graphene aerogel fibers with organic phase change materials by soaking, and coats the fibers with a hydrophobic coating to obtain graphene aerogel intelligent phase change fibers; the Chinese patent with publication number CN 113583634 A prepares graphene aerogel composite fibers by melt spinning after blending modified graphene aerogel composite masterbatch with fiber-forming polymer, then wraps the fibers with phase change materials, and finally uniformly coats the fiber surface with a hydrophobic coating to obtain graphene intelligent temperature-sensitive phase change fibers; in the Chinese patent with publication number CN 115045043 A, a graphene aerogel composite fiber is prepared by melt spinning after blending modified graphene aerogel composite masterbatch with a fiber-forming polymer, then wraps the fibers with phase change materials, and finally uniformly coats the fiber surface with a hydrophobic coating to obtain graphene intelligent temperature-sensitive phase change fibers; In B's Chinese patent, a base layer thermoplastic elastomer nanofiber membrane is first prepared by electrospinning technology; then a phase change material is added to the spinning solution to prepare a phase change layer mixed fiber membrane on the base layer; finally, a thermoplastic elastomer nanofiber membrane is electrospun on the phase change layer, and a conductive material dispersion is coated on the obtained film to obtain a conductive layer.

[0006] Although the above patents have successfully produced electrothermal phase change fibers, there are still some shortcomings. First, because these spinning technologies cannot control the dispersion and orientation of conductive fillers in the fibers and lack the design of conductive network structures, it is often necessary to add excessive amounts of conductive fillers to ensure that the textiles achieve effective electrothermal conversion. However, too much conductive filler will reduce the load of the phase change material, resulting in a decrease in energy storage density; and reducing the content of conductive fillers will lead to insufficient conductivity and electrothermal performance, and reduced electrothermal conversion efficiency. In addition, electrothermal phase change fibers also face the problems of leakage of liquid phase change materials and insufficient flexibility. How to design and manufacture electrothermal phase change textiles with excellent heat storage and electrothermal performance and phase change materials that are not easy to leak remains a challenge. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for preparing an encapsulated electrothermal phase change fiber with an axially oriented conductive network. The prepared encapsulated electrothermal phase change fiber has high electrical conductivity, high energy storage density, high electrothermal conversion efficiency, excellent flexibility and stability, and outstanding thermal management capabilities. The preparation method is simple, low-cost, and has a short production cycle.

[0008] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0009] A method for preparing an encapsulated electrothermal phase change fiber having an axially oriented conductive network, the method comprising the following steps:

[0010] 1) dissolving carbon black in water and dispersing the carbon black, then adding methyl cellulose to prepare a carbon black / methyl cellulose spinning solution;

[0011] 2) squeezing the carbon black / methyl cellulose spinning solution obtained in step 1) into a cold source through a spinning needle on a syringe pump, wherein the spinning solution is gradually frozen upon entering the cold source, and the frozen fibers are collected to produce carbon black / methyl cellulose aerogel fibers with different oriented conductive network structures;

[0012] 3) dipping the carbon black / methyl cellulose aerogel fiber obtained in step 2) into the molten phase change material, taking it out after vacuum impregnation and cooling it at room temperature to obtain the electrothermal phase change fiber;

[0013] 4) The electrothermal phase change fiber obtained in step 3) is coated with a polymer solution by dipping, and the solvent is evaporated by heating to prepare a shell layer package to obtain an encapsulated electrothermal phase change fiber.

[0014] The technical concept of the present invention is that aerogel, as an ultra-light material with a three-dimensional interconnected porous network structure, can adsorb phase change materials through capillary force, and its extremely high porosity provides sufficient space for the loading of functional materials; in addition, by introducing an oriented conductive network structure into the aerogel, the conductivity can be enhanced and effective electrothermal conversion can be achieved when the conductive filler content is low; electrothermal phase change fibers are prepared by preparing aerogel fibers with an oriented conductive network structure and then compounding the phase change material with the fibers; encapsulating the fibers can improve the stability of the fibers, and fixing the phase change material in the fiber core layer by encapsulation is expected to prevent leakage of the phase change material in actual applications.

[0015] In the present invention, methyl cellulose contains methyl (–CH3) groups in its structure, which makes it have better solubility in water and lower hydrophilicity; the hydrophobic properties of the methyl groups help the carbon black particles to be better dispersed in the methyl cellulose. Therefore, this good dispersibility enables the carbon black particles to more effectively form a conductive network through the fibers, thereby improving the conductivity. Compared with methyl cellulose, polymers containing polar groups such as carboxymethyl cellulose have stronger hydrophilicity due to the presence of intrinsically dissociable functional groups such as carboxyl (–COOH) in their structure. This type of cellulose has better solubility in water, but its interaction with carbon black is stronger, making it more difficult to evenly disperse the carbon black particles, affecting the formation of the conductive network and resulting in poor final conductivity.

[0016] In step 1), the mass ratio of carbon black to methyl cellulose is 0.8-1.6:1.

[0017] In step 1), the mass ratio of carbon black to methyl cellulose is 1-1.6:1, which can further improve the electrical conductivity of the electrothermal phase change fiber.

[0018] In step 2), the cooling source is a semiconductor annular cooling source device, the temperature of the semiconductor annular cooling source device is -10 to -50°C, and the extrusion speed of the carbon black / methyl cellulose fiber is set to 1 to 4 ml / h.

[0019] Preferably, the temperature of the semiconductor annular cold source device is -10 to -30°C.

[0020] During the freeze-spinning process, due to the temperature gradient between the cold source and the interior of the fiber, ice crystals will grow in a directional manner along the temperature gradient, and solute molecules will precipitate during the solvent crystallization process. By controlling the temperature of the cold source, the precipitation rate of the solute molecules can be changed to form different fiber morphologies. Therefore, by regulating the freezing temperature, the microstructure of the carbon black / methyl cellulose aerogel fiber can be effectively controlled, thereby constructing aerogel fibers with different pore structures. Regulating the pore structure of aerogel fibers will affect the conductivity of the fibers. This is because according to percolation theory, without changing the content of conductive fillers, optimizing the conductive path can improve the conductivity of the material. Therefore, by increasing the degree of orientation of the conductive network of the aerogel fiber along the axial direction, the conductivity can be improved without changing the content of the conductive fillers.

[0021] In step 2), the carbon black / methyl cellulose aerogel fiber has a three-dimensional porous network structure consisting of macroscopic pores with a pore size of 20 to 170 μm, a porosity of 75 to 85%, and a specific surface area of ​​10 to 30 m 2 / g, conductivity is 40~140S / m.

[0022] The higher the porosity of an aerogel fiber, the more phase change material it can accommodate. Therefore, a higher porosity increases the amount of phase change material that can be loaded into the aerogel. If the porosity is lower, the aerogel has less pore space, and the amount of phase change material loaded is naturally reduced. Phase change enthalpy is the amount of heat absorbed or released by a phase change material during a phase change (e.g., from solid to liquid). Since a higher-porosity aerogel can hold more phase change material, the phase change enthalpy increases. A higher loading means more.

[0023] In step 3), the phase change material is selected from any one of polyethylene glycol, paraffin, polyol, erythritol or polyolefin.

[0024] Preferably, the phase change material is selected from polyethylene glycol or paraffin.

[0025] In step 4), the polymer solution used for coating is selected from a polyurethane solution or a polytetramethylsiloxane solution. The polyurethane solution is a polyurethane / N,N-dimethylformamide solution with a concentration of 10 w / v%. The polytetramethylsiloxane solution is a solution in which polytetramethylsiloxane resin and a curing agent are mixed in a ratio of 10:1 and cured in an oven at 50°C for 15 minutes.

[0026] In step 4), the electrothermal phase change fiber is immersed in the polymer solution for 30 seconds. After being taken out, the excess solution is scraped off using a customized sieve plate with a pore size of 800-1000 μm. The fiber is then placed 5 cm above an 80°C heater and heated for 10 minutes. The number of repeated immersion and drying is 1 to 6 times.

[0027] In step 4), the content of the graphene / methyl cellulose fiber network of the prepared encapsulated electrothermal phase change fiber is 10-25wt%, the content of the phase change material is 55-85wt%, and the rest is the polymer shell layer.

[0028] In step 4), the content of the graphene / methyl cellulose fiber network of the prepared encapsulated electrothermal phase change fiber is 11-18 wt %, the content of the phase change material is 68-82 wt %, and the rest is the polymer shell layer.

[0029] Preferably, the prepared encapsulated electrothermal phase change fiber has a graphene / methyl cellulose fiber network content of 16-18 wt%, a phase change material content of 77-79 wt%, and the rest being a polymer shell layer.

[0030] In step 4), the phase change enthalpy of the prepared encapsulated electrothermal phase change fiber is 85 to 200 J / g.

[0031] The graphene / methylcellulose fiber network prepared by the present invention has a high porosity, so the loading capacity of the phase change material can be increased (a higher loading capacity means that more phase change material can undergo phase change when the temperature changes, thereby absorbing or releasing more heat); the phase change enthalpy is the heat absorbed or released by the phase change material during the phase change process (such as from solid to liquid); because the high-porosity aerogel prepared by the present invention can accommodate more phase change material, the phase change enthalpy will also increase.

[0032] The present invention also provides an application of the encapsulated electrothermal phase change fiber prepared by the above preparation method in personal thermal management and thermal insulation fabrics.

[0033] The encapsulated electrothermal phase change fiber gives the fabric the characteristics of phase change constant temperature, electric heating, energy storage, etc., so that it can regulate the temperature of the human body surface microenvironment and reduce the adverse effects of extreme environments, temperature fluctuations, etc. on the human body. The encapsulated electrothermal phase change fiber of the present invention adopts conventional or unconventional processing technology. It can not only be blended with natural fibers or chemical fibers, but also directly woven into commercial textiles to be processed into electrothermal phase change textiles. It has great application potential in the fields of daily clothing, special protective clothing, etc. When the encapsulated electrothermal phase change fiber is used for personal thermal management, after applying electrical energy to it, its oriented conductive network converts the electrical energy into thermal energy, and the thermal energy is then conducted to the phase change material filled in the conductive network. The phase change material stores thermal energy through solid-liquid phase change and releases thermal energy through liquid-solid phase change when the ambient temperature drops. In addition, the encapsulated electrothermal phase change fiber of the present invention has its phase change material bound by the shell layer in the fiber core layer, which is not easy to leak from the inside of the fiber and has high stability. The encapsulated electrothermal phase change fiber of the present invention has rapid electrothermal responsiveness and can quickly charge the phase change material through electric heating. The high phase change enthalpy enables it to maintain long-term thermal comfort on the body surface through phase change heat release. The excellent mechanical stability and structural stability make it suitable for various extreme environments. Therefore, the encapsulated electrothermal phase change fiber of the present invention is an ideal material for personal thermal management.

[0034] Compared with the prior art, the advantages of the present invention include:

[0035] (1) The encapsulated electrothermal phase change fiber provided by the present invention breaks through the limitation that the energy storage and electrothermal performance of the electrothermal phase change fiber are difficult to balance, and has the advantages of high electrical conductivity, high energy storage density, high electrothermal conversion efficiency, excellent flexibility and stability. It is composed of carbon black / methyl cellulose aerogel fiber containing an oriented conductive network, a phase change material and an encapsulation shell layer; the carbon black / methyl cellulose aerogel fiber serves as the matrix material of the encapsulated electrothermal phase change fiber, which not only has a high electrical conductivity of 40 to 140 S / m, but also has a large porosity of 75 to 85%, providing a large space for the load of the phase change material, and also has a large specific surface area of ​​10 to 30 m 2 / g, the three-dimensional porous network with large specific surface area promotes the conversion and storage of energy; the encapsulation shell structure effectively prevents the leakage of phase change materials and also improves the mechanical properties and hydrophobic properties of the fiber.

[0036] (2) The method for preparing encapsulated electrothermal phase change fibers provided by the present invention adopts freeze spinning, vacuum impregnation and dip coating technology. The preparation process is simple, green and environmentally friendly, and the production cycle is short. At the same time, the raw materials are widely available and the cost is low, which is suitable for large-scale production. It lays the foundation for the multifunctionalization of electrothermal phase change fibers and the expansion of their application in the field of personal thermal management.

[0037] (3) The encapsulated electrothermal phase change fiber provided by the present invention can be used for phase change energy storage, electrothermal conversion and storage. The fabric woven with the fiber has the advantages of fast response speed, high stability, strong adaptability, good flexibility, air permeability and moisture permeability. It shows broad application prospects in personal thermal management and deserves to be widely promoted and applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 These are scanning electron microscope photos of the radial and axial cross sections of the carbon black / methyl cellulose aerogel fibers obtained in Example 1;

[0039] Figure 2 This is a scanning electron microscope photograph of a radial cross section of the electrothermal phase change fiber obtained in Example 1;

[0040] Figure 3 This is a scanning electron microscope photograph of a radial cross section of the encapsulated electrothermal phase change fiber obtained in Example 1;

[0041] Figure 4 The electron microscope images of the radial cross section and axial interface of the carbon black / methyl cellulose aerogel fiber obtained in Example 2;

[0042] Figure 5 The electron microscope images of the radial cross section and axial interface of the carbon black / methyl cellulose aerogel fiber obtained in Example 3;

[0043] Figure 6 The electron microscope images of the radial cross section and axial interface of the carbon black / methyl cellulose aerogel fiber obtained in Example 4;

[0044] Figure 7 is a differential scanning calorimetry curve of the encapsulated phase change composite fiber obtained in Example 1;

[0045] Figure 8 This is an infrared photograph of the encapsulated phase change composite fiber obtained in Example 1 during electrical heating. DETAILED DESCRIPTION

[0046] The specific embodiments of the present invention are further described below.

[0047] In the present invention, unless otherwise specified, the raw materials and equipment used can be purchased from the market or are commonly used in the art. The methods in the embodiments, unless otherwise specified, are all conventional methods in the art.

[0048] The encapsulated electrothermal phase-change fiber prepared by this invention uses a carbon black / methylcellulose aerogel fiber as the matrix material, the fiber interior is filled with a phase-change material, and the exterior is encapsulated with a polymer solution to form a shell. The carbon black / methylcellulose aerogel fiber provides electrical conductivity and electrothermal properties, the phase-change material provides heat storage, and the encapsulation shell provides mechanical properties and prevents leakage of the phase-change material.

[0049] Test method:

[0050] Structural characterization: The orientation and disordered pore structure of the carbon black / methyl cellulose fibers and the morphology of the encapsulated electrothermal phase change fibers were observed using a scanning electron microscope (SU-3500) with an accelerating voltage of 5 kV and a gold spraying time of 90 s. In order to observe the cross-section of the fiber, the fiber was immersed in liquid nitrogen at -196°C. After it was completely frozen, the fiber was broken with tweezers to obtain the cross-section to be observed. The porosity of the carbon black / methyl cellulose fiber was measured using a mercury intrusion instrument (AutoPore IV 9510). The pore size of the carbon black / methyl cellulose fiber was calculated using the following formula:

[0051]

[0052] Where d is the average pore size of the fiber, d length is the pore length of the fiber in the electron microscope image, d width is the pore width of the fiber in the electron microscope image.

[0053] Conductivity Testing: First, remove the encapsulation layer at both ends of the electrothermal phase change fiber and connect the copper tape to the fiber sample using conductive silver glue. Then, connect the leads of a digital multimeter (Keithley 2611B) to the copper tape at both ends of the fiber to measure the resistance of the sample. Calculate the fiber conductivity (κ) using the following formula:

[0054] κ=L / RS (2)

[0055] Where R is the resistance of the fiber, L is the length of the fiber, and S is the cross-sectional area of ​​the fiber.

[0056] Phase change properties characterization: Differential scanning calorimetry (TA-Q200) was used to package the electrothermal phase change fiber for phase change property analysis

[0057] Electrothermal conversion efficiency testing: Copper tape was applied to both ends of the encapsulated electrothermal phase change fiber. The sample was connected to a power supply and a DC voltage was applied, with the current data recorded in real time. The surface temperature of the encapsulated phase change composite fiber was measured using an infrared thermal imager. The distance between the sample and the infrared thermal imager lens was maintained at 30 cm. The infrared thermal imager was used to measure the phase change time of the encapsulated electrothermal phase change fiber during electrical heating, and the electrothermal conversion efficiency was calculated using the following formula:

[0058]

[0059] Where η is the electrothermal conversion efficiency, m is the mass of the encapsulated electrothermal phase change fiber, ΔH m is the phase change enthalpy of the encapsulated electrothermal phase change fiber, U is the voltage applied to the fiber, I is the current passing through the fiber, and t is the time experienced by the fiber phase change process.

[0060] Example 1

[0061] The method for preparing the encapsulated electrothermal phase change fiber in this embodiment includes the following steps:

[0062] 1) Dissolve 10 g of carbon black in 100 ml of water and sonicate for 20 min using an ultrasonic cell disrupter to prepare a nano-monomer dispersion containing stable carbon black. Then, add 10 g of methyl cellulose and stir at 800 rpm for 1 hour to prepare a carbon black / methyl cellulose spinning solution with a carbon black to methyl cellulose concentration of 1:1.

[0063] 2) The carbon black / methyl cellulose spinning solution obtained in step 1) was extruded into a semiconductor copper ring cold source at a temperature of -30°C through a spinning needle on an injection pump at an extrusion rate of 3 ml / h. The extruded fiber diameter was controlled to be 700 μm. The spinning solution was gradually frozen when entering the cold source. The frozen fibers were collected using a reel. The collected fibers were freeze-dried at -60°C and 0.05 mbar for 24 hours. The average pore diameter was 102 μm, the porosity was 83%, and the specific surface area was 24 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 129.9S / m;

[0064] 3) Immersing the carbon black / methylcellulose aerogel fiber obtained in step 2) in molten polyethylene glycol, placing it in a vacuum oven at 60° C. for 5 minutes, then taking it out and cooling it at room temperature to obtain an electrothermal phase change fiber;

[0065] 4) Dissolve 10 g of thermoplastic polyurethane particles in 100 ml of N,N-dimethylformamide and stir at 500 rpm for 24 hours to obtain a 10 w / v% polyurethane encapsulation solution. Immerse the electrothermal phase change fiber obtained in step 3) in the polyurethane solution for 30 seconds, and use a mesh plate with a pore size of 800 μm to scrape off excess solution and heat the fiber at 80°C to evaporate the solvent to prepare the shell encapsulation. Then, place the fiber 5 cm above the 80°C heater and heat for 10 minutes. Repeat the immersion and drying twice to obtain the encapsulated electrothermal phase change fiber.

[0066] The scanning electron microscope photos of the radial and axial cross sections of the carbon black / methyl cellulose aerogel fibers obtained in this example are shown in FIG. Figure 1 a and Figure 1 As shown in b; the scanning electron microscope photo of the radial cross section of the obtained electrothermal phase change fiber is shown in Figure 2 The scanning electron microscope photo of the radial cross section of the obtained encapsulated electrothermal phase change fiber is shown in FIG. Figure 3 Its differential scanning calorimetry curve is shown as Figure 7As shown in the infrared photo of the electric heating Figure 8 shown.

[0067] The present invention prepares carbon black / methyl cellulose aerogel fibers by adopting freeze spinning technology, then vacuum impregnates polyethylene glycol, and dip-coates the fibers with a polyurethane solution to obtain fibers with the advantages of high electrical conductivity, high energy storage density, high electrothermal conversion efficiency, excellent flexibility and stability.

[0068] The encapsulated electrothermal phase change fiber produced by the preparation method of the present invention adopts carbon black / methyl cellulose aerogel fiber containing an oriented conductive network as the substrate. The oriented conductive network structure improves the charge transfer efficiency of the fiber. The aerogel fiber has an electrical conductivity of 102S / m and has a high porosity of 83%, a porosity of 24m 2 / g has the characteristics of a large specific surface area, and achieves excellent electrothermal performance with a small amount of conductive material, allowing more phase change material to be filled inside the fiber, thereby ensuring that the fiber has a high energy storage density. The carbon black / methyl cellulose content of the encapsulated electrothermal phase change fiber is 16wt%, the phase change material content is 79wt%, the conductivity is 80S / m, the phase change enthalpy is 124.5J / g, and the electrothermal conversion efficiency under 20V voltage heating is 96%. In addition, the three-dimensional porous structure of the conductive network helps to quickly conduct heat to the phase change material and the heat can be evenly dispersed throughout the phase change material matrix, avoiding local accumulation of heat in the phase change material, significantly improving the electrothermal conversion efficiency, and the electrothermal conversion efficiency of the encapsulated electrothermal phase change fiber to convert electrical energy into phase change energy can reach up to 96%.

[0069] The encapsulated electrothermal phase change fiber of the present invention maintains stable phase change properties after 50 phase change cycles and electrothermal heating-cooling cycles. This is because polyethylene glycol has stable phase change characteristics. The encapsulated electrothermal phase change fiber of the present invention can still maintain stable electrical conductivity and electrothermal performance when bent or knotted, and phase change material leakage will not occur in high temperature and high pressure environments. This is because the encapsulation layer significantly improves the mechanical properties and structural stability of the encapsulated electrothermal phase change fiber. The fiber of the present invention is woven into a fabric, which can quickly complete phase change charging and maintain a constant temperature for a long time. By testing its hydrophobicity and moisture permeability, it is known that the initial water contact angle of the fabric is 100° and the moisture permeability is 83.8gm -2 h -1 , hydrophobic, with good transmittance, and excellent wearable comfort. Ultimately, the resulting fiber has excellent heat storage and electrothermal properties, with long-term stability, making it very suitable for personal thermal management.

[0070] Example 2

[0071] 1) 10 g of carbon black was dissolved in 100 ml of water and sonicated for 20 minutes using an ultrasonic cell disruptor to prepare a nano-monomer dispersion containing stable carbon black. 10 g of methyl cellulose was then added and stirred at 800 rpm for 1 hour to prepare a carbon black / methyl cellulose spinning solution having a carbon black concentration and a methyl cellulose concentration of 10 wt %.

[0072] 2) The carbon black / methyl cellulose spinning solution obtained in step 1) is extruded into a semiconductor copper ring cold source at a temperature of -10°C through a spinning needle on an injection pump at an extrusion rate of 1 ml / h. The extruded fiber diameter is controlled to be 700 μm. The spinning solution is gradually frozen when entering the cold source. The frozen fibers are collected using a reel. The collected fibers are freeze-dried at -60°C and 0.05 mbar for 24 hours. The average pore diameter is 135 μm, the porosity is 80%, and the specific surface area is 12 m 2 / g, carbon black / methyl cellulose aerogel fiber with a conductivity of 140S / m;

[0073] 3) Immersing the carbon black / methylcellulose aerogel fiber obtained in step 2) in molten polyethylene glycol, placing it in a vacuum oven at 60° C. for 5 minutes, then taking it out and cooling it at room temperature to obtain an electrothermal phase change fiber;

[0074] 4) Dissolve 10 g of thermoplastic polyurethane particles in 100 ml of N,N-dimethylformamide and stir at 500 rpm for 24 hours to obtain a 10 w / v% polyurethane encapsulation solution. Immerse the electrothermal phase change fiber obtained in step 3) in the polyurethane solution for 30 seconds, and use a mesh plate with a pore size of 800 μm to scrape off excess solution and heat the fiber at 80°C to evaporate the solvent to prepare the shell encapsulation. Then, place the fiber 5 cm above the 80°C heater and heat for 10 minutes. Repeat the immersion and drying twice to obtain the encapsulated electrothermal phase change fiber.

[0075] The scanning electron microscope photos of the radial and axial cross sections of the carbon black / methyl cellulose aerogel fibers obtained in this example are shown in FIG. Figure 4 a and Figure 4 As shown in b.

[0076] The encapsulated electrothermal phase change fiber prepared in this embodiment has a carbon black / methyl cellulose content of 17wt%, a phase change material content of 78wt%, an electrical conductivity of 86.8S / m, a phase change enthalpy of 122.8J / g, and an electrothermal conversion efficiency of 98% under 20V voltage heating.

[0077] Example 3

[0078] 1) 10 g of carbon black was dissolved in 100 ml of water and sonicated for 20 minutes using an ultrasonic cell disruptor to prepare a nano-monomer dispersion containing stable carbon black. 10 g of methyl cellulose was then added and stirred at 800 rpm for 1 hour to prepare a carbon black / methyl cellulose spinning solution having a carbon black concentration and a methyl cellulose concentration of 10 wt %.

[0079] 2) The carbon black / methyl cellulose spinning solution obtained in step 1) was extruded into a semiconductor copper ring cold source at a temperature of -50°C through a spinning needle on an injection pump at an extrusion rate of 4 ml / h. The extruded fiber diameter was controlled to be 700 μm. The spinning solution was gradually frozen when entering the cold source. The frozen fibers were collected using a reel. The collected fibers were freeze-dried at -60°C and 0.05 mbar for 24 hours. The average pore diameter was 78 μm, the porosity was 81%, and the specific surface area was 25 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 103S / m;

[0080] 3) Immersing the carbon black / methylcellulose aerogel fiber obtained in step 2) in molten polyethylene glycol, placing it in a vacuum oven at 60° C. for 5 minutes, then taking it out and cooling it at room temperature to obtain an electrothermal phase change fiber;

[0081] 4) Dissolve 10 g of thermoplastic polyurethane particles in 100 ml of N,N-dimethylformamide and stir at 500 rpm for 24 hours to obtain a 10 w / v% polyurethane encapsulation solution. Immerse the electrothermal phase change fiber obtained in step 3) in the polyurethane solution for 30 seconds, and use a mesh plate with a pore size of 800 μm to scrape off excess solution and heat the fiber at 80°C to evaporate the solvent to prepare the shell encapsulation. Then, place the fiber 5 cm above the 80°C heater and heat for 10 minutes. Repeat the immersion and drying twice to obtain the encapsulated electrothermal phase change fiber.

[0082] The scanning electron microscope photos of the radial and axial cross sections of the carbon black / methyl cellulose aerogel fibers obtained in this example are shown in FIG. Figure 5 a and Figure 5 As shown in b.

[0083] The encapsulated electrothermal phase change fiber prepared in this embodiment has a carbon black / methyl cellulose content of 17 wt %, a phase change material content of 78 wt %, an electrical conductivity of 64.2 S / m, a phase change enthalpy of 122.7 J / g, and an electrothermal conversion efficiency of 93% under 20 V voltage heating.

[0084] Example 4

[0085] 1) 8 g of carbon black was dissolved in 100 ml of water and sonicated for 20 minutes using an ultrasonic cell disrupter to prepare a nano-monomer dispersion containing stable carbon black. 8 g of methyl cellulose was then added and stirred at 800 rpm for 1 hour to prepare a carbon black / methyl cellulose spinning solution having a carbon black concentration of 8 wt% and a methyl cellulose concentration of 10 wt%;

[0086] 2) The carbon black / methyl cellulose spinning solution obtained in step 1) was extruded into a semiconductor copper ring cold source at a temperature of -30°C through a spinning needle on an injection pump at an extrusion rate of 3 ml / h. The extruded fiber diameter was controlled to be 700 μm. The spinning solution was gradually frozen when entering the cold source. The frozen fibers were collected using a reel. The collected fibers were freeze-dried at -60°C and 0.05 mbar for 24 hours. The average pore diameter was 175 μm, the porosity was 84%, and the specific surface area was 25 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 98.2S / m;

[0087] 3) Immersing the carbon black / methylcellulose aerogel fiber obtained in step 2) in molten polyethylene glycol, placing it in a vacuum oven at 60° C. for 5 minutes, then taking it out and cooling it at room temperature to obtain an electrothermal phase change fiber;

[0088] 4) Dissolve 10 g of thermoplastic polyurethane particles in 100 ml of N,N-dimethylformamide and stir at 500 rpm for 24 hours to obtain a 10 w / v% polyurethane encapsulation solution. Immerse the electrothermal phase change fiber obtained in step 3) in the polyurethane solution for 30 seconds, and use a mesh plate with a pore size of 800 μm to scrape off excess solution and heat the fiber at 80°C to evaporate the solvent to prepare the shell encapsulation. Then, place the fiber 5 cm above the 80°C heater and heat for 10 minutes. Repeat the immersion and drying twice to obtain the encapsulated electrothermal phase change fiber.

[0089] The encapsulated electrothermal phase change fiber prepared in this embodiment has a carbon black / methyl cellulose content of 15wt%, a phase change material content of 80wt%, an electrical conductivity of 61.8S / m, a phase change enthalpy of 126.1J / g, and an electrothermal conversion efficiency of 81% under 20V voltage heating.

[0090] Example 5

[0091] 1) 12 g of carbon black was dissolved in 100 ml of water and sonicated for 20 minutes using an ultrasonic cell disrupter to prepare a nano-monomer dispersion in which carbon black was stably present. 8 g of methyl cellulose was then added and stirred at 800 rpm for 1 hour to prepare a carbon black / methyl cellulose spinning solution having a carbon black concentration of 12 wt % and a methyl cellulose concentration of 10 wt %.

[0092] 2) The carbon black / methyl cellulose spinning solution obtained in step 1) was extruded into a semiconductor copper ring cold source at a temperature of -30°C through a spinning needle on an injection pump at an extrusion rate of 3 ml / h. The extruded fiber diameter was controlled to be 700 μm. The spinning solution was gradually frozen when entering the cold source. The frozen fibers were collected using a reel. The collected fibers were freeze-dried at -60°C and 0.05 mbar for 24 hours. The average pore diameter was 98 μm, the porosity was 79%, and the specific surface area was 21 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 135S / m;

[0093] 3) Immersing the carbon black / methylcellulose aerogel fiber obtained in step 2) in molten polyethylene glycol, placing it in a vacuum oven at 60° C. for 5 minutes, then taking it out and cooling it at room temperature to obtain an electrothermal phase change fiber;

[0094] 4) Dissolve 10 g of thermoplastic polyurethane particles in 100 ml of N,N-dimethylformamide and stir at 500 rpm for 24 hours to obtain a 10 w / v% polyurethane encapsulation solution. Immerse the electrothermal phase change fiber obtained in step 3) in the polyurethane solution for 30 seconds, and use a mesh plate with a pore size of 800 μm to scrape off excess solution and heat the fiber at 80°C to evaporate the solvent to prepare the shell encapsulation. Then, place the fiber 5 cm above the 80°C heater and heat for 10 minutes. Repeat the immersion and drying twice to obtain the encapsulated electrothermal phase change fiber.

[0095] The encapsulated electrothermal phase change fiber prepared in this embodiment has a carbon black / methyl cellulose content of 17 wt %, a phase change material content of 78 wt %, an electrical conductivity of 83.1 S / m, a phase change enthalpy of 123.5 J / g, and an electrothermal conversion efficiency of 98% under 20 V voltage heating.

[0096] Example 6

[0097] The difference from Example 4 is that the carbon black concentration is 14 wt %.

[0098] The average pore size of the prepared sample is 92 μm, the porosity is 79%, and the specific surface area is 29 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 138.5S / m.

[0099] The encapsulated electrothermal phase change fiber prepared in this embodiment has a carbon black / methyl cellulose content of 17 wt %, a phase change material content of 78 wt %, an electrical conductivity of 85.2 S / m, a phase change enthalpy of 123.0 J / g, and an electrothermal conversion efficiency of 98% under 20 V voltage heating.

[0100] Example 7

[0101] The difference from Example 4 is that the carbon black concentration is 16 wt %.

[0102] The average pore size of the prepared sample in this embodiment is 88 μm, the porosity is 78%, and the specific surface area is 30 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 145.1S / m.

[0103] The encapsulated electrothermal phase change fiber prepared in this embodiment has a carbon black / methyl cellulose content of 18 wt %, a phase change material content of 77 wt %, an electrical conductivity of 88.7 S / m, a phase change enthalpy of 122.7 J / g, and an electrothermal conversion efficiency of 99% under 20 V voltage heating.

[0104] Example 8

[0105] 1) 10 g of carbon black was dissolved in 100 ml of water and sonicated for 20 minutes using an ultrasonic cell disruptor to prepare a nano-monomer dispersion containing stable carbon black. 10 g of methyl cellulose was then added and stirred at 800 rpm for 1 hour to prepare a carbon black / methyl cellulose spinning solution having a carbon black concentration and a methyl cellulose concentration of 10 wt %.

[0106] 2) The carbon black / methyl cellulose spinning solution obtained in step 1) was extruded into a semiconductor copper ring cold source at a temperature of -30°C through a spinning needle on an injection pump at an extrusion rate of 3 ml / h. The extruded diameter of the fiber was controlled to be 700 μm. The spinning solution was gradually frozen when entering the cold source. The frozen fiber was collected using a reel. The collected fiber was freeze-dried at -60°C and 0.05 mbar for 24 hours. The average pore diameter was 170 μm, the porosity was 83%, and the specific surface area was 24 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 130S / m;

[0107] 3) immersing the carbon black / methyl cellulose aerogel fiber obtained in step 2) in a molten paraffin solution, placing the fiber in a vacuum oven at 60° C. for 5 minutes, then taking the fiber out and cooling it at room temperature to obtain an electrothermal phase change fiber;

[0108] 4) Dissolve 10 g of thermoplastic polyurethane particles in 100 ml of N,N-dimethylformamide and stir at 500 rpm for 24 hours to obtain a 10 w / v% polyurethane encapsulation solution. Immerse the electrothermal phase change fiber obtained in step 3) in the polyurethane solution for 30 seconds, and use a mesh plate with a pore size of 800 μm to scrape off excess solution and heat the fiber at 80°C to evaporate the solvent to prepare the shell encapsulation. Then, place the fiber 5 cm above the 80°C heater and heat for 10 minutes. Repeat the immersion and drying twice to obtain the encapsulated electrothermal phase change fiber.

[0109] The encapsulated electrothermal phase change fiber prepared in this embodiment has a carbon black / methyl cellulose content of 17 wt %, a phase change material content of 77 wt %, an electrical conductivity of 78.4 S / m, a phase change enthalpy of 193.7 J / g, and an electrothermal conversion efficiency of 94% under 20 V voltage heating.

[0110] Example 9

[0111] 1) 10 g of carbon black was dissolved in 100 ml of water and sonicated for 20 minutes using an ultrasonic cell disruptor to prepare a nano-monomer dispersion containing stable carbon black. 10 g of methyl cellulose was then added and stirred at 800 rpm for 1 hour to prepare a carbon black / methyl cellulose spinning solution having a carbon black concentration and a methyl cellulose concentration of 10 wt %.

[0112] 2) The carbon black / methyl cellulose spinning solution obtained in step 1) was extruded into a semiconductor copper ring cold source at a temperature of -30°C through a spinning needle on an injection pump at an extrusion rate of 3 ml / h. The extruded diameter of the fiber was controlled to be 700 μm. The spinning solution was gradually frozen when entering the cold source. The frozen fiber was collected using a reel. The collected fiber was freeze-dried at -60°C and 0.05 mbar for 24 hours. The average pore diameter was 170 μm, the porosity was 83%, and the specific surface area was 24 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 130S / m;

[0113] 3) immersing the carbon black / methyl cellulose aerogel fiber obtained in step 2) into a molten erythritol solution, placing the fiber in a vacuum oven at 60° C. for 5 minutes, then removing the fiber and cooling it at room temperature to obtain an electrothermal phase change fiber;

[0114] 4) Dissolve 10 g of thermoplastic polyurethane particles in 100 ml of N,N-dimethylformamide and stir at 500 rpm for 24 hours to obtain a 10 w / v% polyurethane encapsulation solution. Immerse the electrothermal phase change fiber obtained in step 3) in the polyurethane solution for 30 seconds, and use a mesh plate with a pore size of 800 μm to scrape off excess solution and heat the fiber at 80°C to evaporate the solvent to prepare the shell encapsulation. Then, place the fiber 5 cm above the 80°C heater and heat for 10 minutes. Repeat the immersion and drying twice to obtain the encapsulated electrothermal phase change fiber.

[0115] The encapsulated electrothermal phase change fiber prepared in this embodiment has a carbon black / methyl cellulose content of 13wt%, a phase change material content of 77wt%, an electrical conductivity of 78.4S / m, a phase change enthalpy of 66.7J / g, and an electrothermal conversion efficiency of 98% under 20V voltage heating.

[0116] Example 10

[0117] 1) 10 g of carbon black was dissolved in 100 ml of water and sonicated for 20 minutes using an ultrasonic cell disruptor to prepare a nano-monomer dispersion containing stable carbon black. 10 g of methyl cellulose was then added and stirred at 800 rpm for 1 hour to prepare a carbon black / methyl cellulose spinning solution having a carbon black concentration and a methyl cellulose concentration of 10 wt %.

[0118] 2) The carbon black / methyl cellulose spinning solution obtained in step 1) was extruded into a semiconductor copper ring cold source at a temperature of -30°C through a spinning needle on an injection pump at an extrusion rate of 3 ml / h. The extruded diameter of the fiber was controlled to be 700 μm. The spinning solution was gradually frozen when entering the cold source. The frozen fiber was collected using a reel. The collected fiber was freeze-dried at -60°C and 0.05 mbar for 24 hours. The average pore diameter was 170 μm, the porosity was 83%, and the specific surface area was 24 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 130S / m;

[0119] 3) Immersing the carbon black / methylcellulose aerogel fiber obtained in step 2) in molten polyethylene glycol, placing it in a vacuum oven at 60° C. for 5 minutes, then taking it out and cooling it at room temperature to obtain an electrothermal phase change fiber;

[0120] 4) polytetramethylsiloxane resin and curing agent were mixed in a ratio of 10:1, and the solution was cured in a 50°C oven for 15 minutes to obtain a polytetramethylsiloxane solution. The electrothermal phase change fiber obtained in step 3) was immersed in the polytetramethylsiloxane solution for 30 seconds, and the excess solution was scraped off using a mesh plate with a pore size of 800 μm and heated by an 80°C heater to evaporate the solvent to prepare the shell encapsulation. The fiber was then placed 5 cm above the 80°C heater and heated for 10 minutes. The immersion and drying were repeated twice to obtain the encapsulated electrothermal phase change fiber.

[0121] The encapsulated electrothermal phase change fiber prepared in this embodiment has a carbon black / methyl cellulose content of 16 wt %, a phase change material content of 79 wt %, an electrical conductivity of 79.8 S / m, a phase change enthalpy of 124.6 J / g, and an electrothermal conversion efficiency of 96% under 20 V voltage heating.

[0122] Example 11

[0123] 1) 10 g of carbon black was dissolved in 100 ml of water and sonicated for 20 minutes using an ultrasonic cell disruptor to prepare a nano-monomer dispersion containing stable carbon black. 10 g of methyl cellulose was then added and stirred at 800 rpm for 1 hour to prepare a carbon black / methyl cellulose spinning solution having a carbon black concentration and a methyl cellulose concentration of 10 wt %.

[0124] 2) The carbon black / methyl cellulose spinning solution obtained in step 1) was extruded into a semiconductor copper ring cold source at a temperature of -30°C through a spinning needle on an injection pump at an extrusion rate of 3 ml / h. The extruded diameter of the fiber was controlled to be 700 μm. The spinning solution was gradually frozen when entering the cold source. The frozen fiber was collected using a reel. The collected fiber was freeze-dried at -60°C and 0.05 mbar for 24 hours. The average pore diameter was 170 μm, the porosity was 83%, and the specific surface area was 24 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 130S / m;

[0125] 3) Immersing the carbon black / methylcellulose aerogel fiber obtained in step 2) in molten polyethylene glycol, placing it in a vacuum oven at 60° C. for 5 minutes, then taking it out and cooling it at room temperature to obtain an electrothermal phase change fiber;

[0126] 4) Dissolve 10 g of thermoplastic polyurethane particles in 100 ml of N,N-dimethylformamide and stir at 500 rpm for 24 hours to obtain a 10 w / v% polyurethane encapsulation solution. Immerse the electrothermal phase change fiber obtained in step 3) in the polyurethane solution for 30 seconds, and use a mesh plate with a pore size of 1000 μm to scrape off excess solution and heat the fiber at 80°C to evaporate the solvent to prepare the shell encapsulation. Then, place the fiber 5 cm above the 80°C heater and heat for 10 minutes. Repeat the immersion and drying 6 times to obtain the encapsulated electrothermal phase change fiber.

[0127] The encapsulated electrothermal phase change fiber prepared in this embodiment has a carbon black / methyl cellulose content of 11 wt %, a phase change material content of 68 wt %, an electrical conductivity of 51.6 S / m, a phase change enthalpy of 124.6 J / g, and an electrothermal conversion efficiency of 97% under 20 V voltage heating.

[0128] Comparative Example 1

[0129] 1) 10 g of carbon black was dissolved in 100 ml of water and sonicated for 20 minutes using an ultrasonic cell disruptor to prepare a nano-monomer dispersion containing stable carbon black. 10 g of methyl cellulose was then added and stirred at 800 rpm for 1 hour to prepare a carbon black / methyl cellulose spinning solution having a carbon black concentration and a methyl cellulose concentration of 10 wt %.

[0130] 2) The carbon black / methyl cellulose spinning solution obtained in step 1) is extruded into a liquid nitrogen cold source at a temperature of -196°C through a spinning needle on an injection pump at an extrusion rate of 4 ml / h. The extruded fiber diameter is controlled to be 700 μm. The spinning solution is gradually frozen when entering the cold source. The frozen fibers are collected using a reel. The collected fibers are freeze-dried at -60°C and 0.05 mbar for 24 hours. The average pore diameter is 25 μm, the porosity is 82%, and the specific surface area is 30 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 83S / m;

[0131] 3) Immersing the carbon black / methylcellulose aerogel fiber obtained in step 2) in molten polyethylene glycol, placing it in a vacuum oven at 60° C. for 5 minutes, then taking it out and cooling it at room temperature to obtain an electrothermal phase change fiber;

[0132] 4) Dissolve 10 g of thermoplastic polyurethane particles in 100 ml of N,N-dimethylformamide and stir at 500 rpm for 24 hours to obtain a 10 w / v% polyurethane encapsulation solution. Immerse the electrothermal phase change fiber obtained in step 3) in the polyurethane solution for 30 seconds, and use a mesh plate with a pore size of 800 μm to scrape off excess solution and heat the fiber at 80°C to evaporate the solvent to prepare the shell encapsulation. Then, place the fiber 5 cm above the 80°C heater and heat for 10 minutes. Repeat the immersion and drying twice to obtain the encapsulated electrothermal phase change fiber.

[0133] The encapsulated electrothermal phase change fiber prepared in this comparative example has a carbon black / methyl cellulose content of 16 wt %, a phase change material content of 79 wt %, an electrical conductivity of 52.5 S / m, a phase change enthalpy of 124.2 J / g, and an electrothermal conversion efficiency of 80% under 20 V voltage heating.

[0134] Comparative Example 2

[0135] The difference from the embodiment is that graphite powder is used instead of carbon black.

[0136] The average pore diameter of the comparative example is 98 μm, the porosity is 83%, and the specific surface area is 24 m 2 / g, graphite / methyl cellulose aerogel fiber with an electrical conductivity of 97.5S / m.

[0137] The encapsulated electrothermal phase change fiber prepared in this comparative example has a carbon black / methyl cellulose content of 16 wt %, a phase change material content of 79 wt %, an electrical conductivity of 59.7 S / m, a phase change enthalpy of 124.3 J / g, and an electrothermal conversion efficiency of 86% under 20 V voltage heating.

[0138] Comparative Example 3

[0139] Different from step 1) and step 2) of Example 1:

[0140] 1) Preparation of carbon black / polyurethane spinning solution: 10 g of carbon black was dissolved in 100 ml of N,N-dimethylformamide (the solvent for freeze spinning was water) and sonicated for 20 min using an ultrasonic cell disruptor to prepare a nano-monomer dispersion containing a stable carbon black. 15 g of thermoplastic polyurethane particles was then added and stirred at 500 rpm for 8 h to obtain a uniform spinning solution.

[0141] 2) After loading the prepared carbon black / TPU spinning solution into a syringe, the solution is extruded into a coagulation bath using anhydrous ethanol at a rate of 4 ml / h using a microsyringe pump. The coagulation bath is composed of anhydrous ethanol. Wet spinning principle: Due to the different solubilities of TPU in ethanol and DMF, the spinning solution undergoes microscopic phase separation upon entering the coagulation bath, resulting in solidification and forming carbon black / TPU composite fibers. The fibers are then continuously collected by a take-up reel motor and dried in air at 40°C to produce carbon black / TPU composite aerogel fibers.

[0142] The average pore size of the comparative example is 22 μm, the porosity is 68%, and the specific surface area is 33 m 2 / g, graphite / methyl cellulose aerogel fiber with an electrical conductivity of 63.6S / m.

[0143] The encapsulated electrothermal phase change fiber prepared in this comparative example has a graphite / methyl cellulose content of 15wt%, a phase change material content of 69wt%, an electrical conductivity of 38.2S / m, a phase change enthalpy of 108.8J / g, and an electrothermal conversion efficiency of 43% under heating at a voltage of 20V.

[0144] Comparative Example 4

[0145] The difference from Example 1 is that carboxymethyl cellulose is used instead of methyl cellulose.

[0146] The average pore diameter of the comparative example is 103 μm, the porosity is 83%, and the specific surface area is 25 m 2 / g, carbon black / carboxymethyl cellulose aerogel fiber with an electrical conductivity of 57.7S / m.

[0147] The encapsulated electrothermal phase change fiber prepared in this comparative example has a carbon black / carboxymethyl cellulose content of 16 wt %, a phase change material content of 79 wt %, an electrical conductivity of 37.6 S / m, a phase change enthalpy of 124.2 J / g, and an electrothermal conversion efficiency of 38% under 20 V voltage heating.

[0148] Comparative Example 5

[0149] 1) 6 g of carbon black was dissolved in 100 ml of water and sonicated for 20 minutes using an ultrasonic cell disrupter to prepare a nano-monomer dispersion containing stable carbon black. 10 g of methyl cellulose was then added and stirred at 800 rpm for 1 hour to prepare a carbon black / methyl cellulose spinning solution having a carbon black concentration of 6 wt% and a methyl cellulose concentration of 10 wt%;

[0150] 2) The carbon black / methyl cellulose spinning solution obtained in step 1) was extruded into a semiconductor copper ring cold source at a temperature of -30°C through a spinning needle on an injection pump at an extrusion rate of 3 ml / h. The extruded fiber diameter was controlled to be 700 μm. The spinning solution was gradually frozen when entering the cold source. The frozen fibers were collected using a reel. The collected fibers were freeze-dried at -60°C and 0.05 mbar for 24 hours. The average pore diameter was 113 μm, the porosity was 86%, and the specific surface area was 26 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 39.8S / m;

[0151] 3) Immersing the carbon black / methylcellulose aerogel fiber obtained in step 2) in molten polyethylene glycol, placing it in a vacuum oven at 60° C. for 5 minutes, then taking it out and cooling it at room temperature to obtain an electrothermal phase change fiber;

[0152] 4) Dissolve 10 g of thermoplastic polyurethane particles in 100 ml of N,N-dimethylformamide and stir at 500 rpm for 24 hours to obtain a 10 w / v% polyurethane encapsulation solution. Immerse the electrothermal phase change fiber obtained in step 3) in the polyurethane solution for 30 seconds, and use a mesh plate with a pore size of 800 μm to scrape off excess solution and heat the fiber at 80°C to evaporate the solvent to prepare the shell encapsulation. Then, place the fiber 5 cm above the 80°C heater and heat for 10 minutes. Repeat the immersion and drying twice to obtain the encapsulated electrothermal phase change fiber.

[0153] The encapsulated electrothermal phase change fiber prepared in this comparative example has a carbon black / methyl cellulose content of 15wt%, a phase change material content of 80wt%, an electrical conductivity of 24.3S / m, a phase change enthalpy of 126.7J / g, and an electrothermal conversion efficiency of 36% under 20V voltage heating.

[0154] Comparative Example 6

[0155] The difference from Example 1 is that the carbon black concentration is 4 wt %.

[0156] The average pore diameter of the comparative example is 119 μm, the porosity is 87%, and the specific surface area is 31 m 2 / g, carbon black / methyl cellulose aerogel fiber with an electrical conductivity of 11.4S / m.

[0157] The encapsulated electrothermal phase change fiber prepared in this comparative example has a carbon black / methyl cellulose content of 17wt%, a phase change material content of 78wt%, an electrical conductivity of 85.2S / m, a phase change enthalpy of 123.0J / g, and an electrothermal conversion efficiency of 98% under 20V voltage heating.

[0158] Comparative Example 7

[0159] The difference from Example 1 is that the carbon black concentration is 18 wt %.

[0160] The viscosity of the spinning solution in this comparative example is too high to be extruded and spun into fibers.

[0161] Through the above embodiments and comparative examples, the encapsulated electrothermal phase change fiber obtained by the above technical solution of the present invention has high electrical conductivity, high energy storage density, high electrothermal conversion efficiency, excellent mechanical flexibility and phase change stability, and has good applications in phase change energy storage, active electrothermal, and energy storage. The preparation process is simple, green and environmentally friendly, and the production cycle is short. At the same time, the raw material source is wide and the cost is low, which is suitable for large-scale production. It has broad application prospects in the field of personal thermal management.

[0162] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing an encapsulated electrothermal phase change fiber having an axially oriented conductive network, characterized in that: The method comprises the following steps: 1) dissolving carbon black in water and dispersing the carbon black, then adding methyl cellulose to prepare a carbon black / methyl cellulose spinning solution; 2) squeezing the carbon black / methyl cellulose spinning solution obtained in step 1) into a cold source through a spinning needle on a syringe pump, wherein the spinning solution is gradually frozen upon entering the cold source, and the frozen fibers are collected to produce carbon black / methyl cellulose aerogel fibers with different oriented conductive network structures; 3) dipping the carbon black / methyl cellulose aerogel fiber obtained in step 2) into the molten phase change material, taking it out after vacuum impregnation and cooling it at room temperature to obtain the electrothermal phase change fiber; 4) coating the electrothermal phase change fiber obtained in step 3) with a polymer solution by dip coating, and heating to volatilize the solvent to prepare a shell layer encapsulation to obtain an encapsulated electrothermal phase change fiber; The mass ratio of carbon black to methyl cellulose is 0.8-1.6:1; The cold source is a semiconductor annular cold source device, and the temperature of the semiconductor annular cold source device is -10 to -50°C.

2. The preparation method according to claim 1, characterized in that In step 1), the mass ratio of carbon black to methyl cellulose is 1.2-1.6:

1.

3. The preparation method according to claim 1, characterized in that In step 2), the extrusion speed of the carbon black / methyl cellulose fiber is set to 1-4 ml / h.

4. The preparation method according to claim 1, characterized in that In step 2), the carbon black / methyl cellulose aerogel fiber has a three-dimensional porous network structure consisting of macroscopic pores with a pore size of 20 to 170 μm, a porosity of 75 to 85%, and a specific surface area of ​​10 to 30 m 2 / g, conductivity is 40~140S / m.

5. The preparation method according to claim 1, characterized in that In step 3), the phase change material is selected from any one of polyethylene glycol, paraffin, polyol, erythritol or polyolefin.

6. The preparation method according to claim 1, characterized in that In step 4), the content of the graphene / methyl cellulose fiber network of the prepared encapsulated electrothermal phase change fiber is 10-25wt%, the content of the phase change material is 55-85wt%, and the rest is the polymer shell layer.

7. The preparation method according to claim 1, characterized in that In step 4), the content of the graphene / methyl cellulose fiber network of the prepared encapsulated electrothermal phase change fiber is 11-18 wt %, the content of the phase change material is 68-82 wt %, and the rest is the polymer shell layer.

8. The preparation method according to claim 1, characterized in that In step 4), the phase change enthalpy of the prepared encapsulated electrothermal phase change fiber is 85 to 200 J / g.

9. Use of the encapsulated electrothermal phase change fiber prepared by the preparation method according to any one of claims 1 to 8 in personal thermal management and warming fabrics.

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